<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Vue</title>
  <script src="https://cdn.jsdelivr.net/npm/vue"></script>
</head>
<body>
<div id="app">
  <!-- 变量city就是你下拉选择项的value值 -->
  <h2>下拉单选框</h2>
  <div id="select">
    <select v-model="selected">
      <option disabled value="">请选择</option>
      <option>北京</option>
      <option>上海</option>
      <option>广州</option>
      <option>深圳</option>
      <option>杭州</option>
    </select>
    <span>你选中的城市: {{ selected }}</span>
  </div>
</div>
<script>
  new Vue({
    el: '#select',
    data: {
      selected: '' // 使默认选择'请选择'
    }
  });
</script>
</body>
</html>